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Energy Storage in Belgium

Belgium's energy system is about to face major changes in the forthcoming decades. The massive integration of renewables energy sources into the grid coupled with the future nuclear phase-out and the closings of gas power plants will entail a complete redesign of the energy system. Ensuring the balance of the grid will become even more delicate with the increase of intermittent energies. For that reason, energy storage must be investigated as a solution to cope with these arising challenges and to help with the energy transition. Sia Partners provides an overview of the existing energy storage technologies as well as the innovations developped in that field in order to determine how it could eventually be integrated as a future component of the Belgian energy system.

? Changes in Belgian generation mix will bring new challenges

The increase of intermittent generation will challenge grid stability

In Belgium, the European 20-20-20 objectives has translated into an objective of approximately 19% of the generated electricity coming from renewable sources by 2020 compared to 6 % currently. As hydropower is already well exploited, the deployment of biomass, wind and solar photovoltaic is considered to reach this ambitious target.

Source: Eurostat, EWEA, EPIA, Belgium NREAP

As illustrated above, wind and solar PV production will respectively be multiplied by five and three between 2011 and 2020. This generation is intermittent and dispersed as it depends on weather and is located where conditions are the most favourable to produce electricity. With a fuel mix containing 11% of intermittent production in 2020, as compared to only 3 % in 2011, the energy system will deal with a production whose level can change suddenly with large amplitude, potentially creating grid stability issues such as congestions or imbalances in case of high or low generation respectively.

Peak power plants closings will make peak load management more delicate

In Belgium, load can reach more than 14000 MW for some winter days. During those periods of highest consumption, peak power plants, essentially gas turbines, can be quickly turned on to cover the surge in electricity demand. Generation coming from peak power plants is costly and often more expensive than the electricity that can be bought on the market. Moreover the unclear injection tariff framework that is applied to producers makes the electricity generated by Belgian gas/oil power plants even less competitive. This has led several market players to close their gas power plants. Up to now, these foreseen closings sum up to more than 2500 MW causing potential issues when dealing with peak demand.

Nuclear phase-out by 2025 will entail a shortage of production capacities

Belgium's energy system is about to face an important future challenge as the Belgian government decided in 2003 that our country would definitely step out of nuclear generation in 2025, which represents almost 6000 MW of installed capacity. Currently, more than a third of generated electricity comes from nuclear energy, which constitutes a predictable and stable production that might be partly replaced by renewable generation.

Forthcoming need for new installed capacity in Belgium

CREG asserted in 2011 that a lack of base and peak installed capacity would occur up to 2020, essentially because of nuclear phase-out, if possible electricity imports were not taken into account. This lack of capacity starts to be significant in 2015. The situation then worsens until 2020 where investments in more than 4000 MW become necessary in order to ensure stability and reliability of the Belgian power system.

Source: CREG

? Increasing need to develop energy storage

Energy storage technologies can help dealing with future challenges

Basically, energy storage consists in storing the electricity surplus when production exceeds demand and releasing it when demand exceeds production. The main issue relates to the impossibility to store electricity directly in its original form in large volumes. Therefore it is most of the time indirectly stored through a mechanical, thermal, chemical or electrochemical transformation into another form of energy, which implies to do the reverse transformation in order to recover electrical power. The table below summarizes the main current technologies and their features that define for which particular application a given technology is more suitable than another. They also determine at what level of the energy system the technology can be considered and used.

Currently, only pumped hydro and some conventional batteries, such as lead acid ones, are mature while all other technologies are at earlier stage of development. The technologies also differ in terms of costs and the given figures must only be seen as indicative estimations of interval. Indeed, the economics of a storage technology can only be assessed within the context of a particular application.

Energy storage is a solution to deal with the forthcoming challenges that will occur in the Belgian energy system. Examples of these challenges are stabilizing the grid, limiting GHG emission, dealing with intermittency, resolving congestions, dealing with peak load and ensuring voltage and frequency stability. Moreover, energy storage is supposed to bring both environmental and economic benefits to the power system. First it will enable the integration of RES by reducing the need of peak power plants and hereby limiting their negative environmental impacts caused by constant start-ups and shut downs. Second it would reduce dependence on fossil fuel imports and enable electricity to be consumed locally, which will for instance limit the need of investments in transmission lines, that are estimated around 1.9 billion € in Belgium by 2020.

For some years, the technologies that are the most mature or promising are subject to innovation mainly in order to bypass the constraints imposed by the conventional technologies but also to improve the efficiency. The table above focuses on pumped hydro- (PHS) and compressed air energy storage (CAES), used for large-scale applications. Indeed the further development of hydro pumped storage facilities is quite limited in Europe and innovative solutions must be investigated, such as the use of underground caverns or the construction of the upper basin in the coastal areas. Concerning CAES power plants, the future generation should improve the efficiency from 50%, for the two current power plants, to 70% by storing both air and heat.

Despite all the expected advantages, these new forms of technologies also imply higher investment costs for the moment but further developments are expected to push technology costs down. Currently these innovations are already exploited or their feasibility is being studied.

? Current status of energy storage capacity

Pumped hydro storage is the most widespread storage technology with up to 110 GW of installed capacity worldwide (40 GW in Europe) that represents 99% of total storage capacity. Additional 27 GW are planned for Europe by 2020. As illustrated on the graph, Europe has also a strong position on other large scale energy storage market with one CAES power plant and projects in other technologies. However the USA and Japan invest a lot in both conventional and innovative energy storage which position them as world leaders. Germany is a leader in Europe because all sorts of storage technologies are developed in this country in order to cope with the significant rise of intermittent generation. Germany decided that the deployment of large-scale storage capacity has become necessary to integrate this new form of production. In its report "Transformation of the Energy System", the German government announces that more than 10 GW of installed capacity dedicated to energy storage will be built by 2020 in order to facilitate the control of intermittent generation.

Source: EPRI

Current situation in Belgium

In Belgium, the only storage facilities are the two hydro power plants located in Coo and Platte Taille. They have a capacity content of 1100 and 136 MW respectively and the Coo power plant can store up to 5 GWh. They were initially built in order to regulate electricity generation coming from the nuclear reactor in Tihange but are now increasingly used as a tool to balance generation and load on the grid. Such power plants constitute good storage facilities but as they come with geographical and environmental constraints, a further massive deployment cannot be envisaged in Belgium.

? Assessment of possible development of energy storage in Belgium

Determination of possible storage technologies in Belgium: the secret potential of abandoned mines

Belgium faces three different scenarios to cope with the increasing need of investments in new capacities. First, the Belgian government could extend the lifetime of three nuclear facilities beyond 2015. Second, investments can be made only in gas power plants to cover both base and peak load. Finally, the third scenario, debated below, relies partially on storage technologies to cover base and peak load, the residual capacities being covered by gas power plants.

In order to analyse the scenario implying the use of electricity storage, the projected situation in 2020 as well as the geological characteristics of the countries are used as a starting point to determine the most suitable storage technologies to develop in Belgium.

To cover peak load storage technologies with quick reaction time and high energy output/content are potential candidates. Among the different alternatives, pumped hydro storage, CAES and hydrogen are the best options to consider. However, they all come with drawbacks. First, the early stage of development of hydrogen does not make it economically viable or conceivable for large applications before 2030. Second, new generation of CAES power plants are not investigated in Belgium by the European energy players. Finally, the future potential of PHS in Belgium seems at first quite limited given the absence of unexploited geological zones that offer an interesting depth difference needed between the two reservoirs. This is the reason why more challenging sites, like located underground, must be looked for. Indeed old unexploited mines could seriously serve as sites for the production of hydroelectricity. In particular, those located in the Walloon basins near Anderlue could store electricity in this innovative way as they were exploited during the past in two phases which created two isolated parts in the same mine separated by a sufficient depth difference. Given the past of Belgium in the extraction's sector, many coalmines are closed or abandoned and could possibly be used for that purpose. Two similar projects are on-going in the United States, using abandoned underground limestone and iron mines. Moreover, exploiting underground mines limits the environmental impact and consequently the problematic public acceptance of such important installation. However, despite its numerous advantages, such a project still requires high capital expenses.

Base load could be partly covered by storage technologies that support RES in order to control intermittency in production. Wind installed capacity in 2020 will be split in on shore and off shore farms that have different needs and specifications in term of storage. Off shore wind farms will be concentrated in 6 sites that represent each between 165 and 400 MW, totalising 4000 MW of installed capacity by 2020. In order to moderate the intermittency of such a production, a project has been initiated in 2013 and would consist in the construction of an artificial island off the coast of Belgium. The electricity storage would be based on the exploitation of seawater pumped hydro technology. Indeed, the island would contain the lower basin situated 30 meters below the sea level, where the water would be pumped in or out in case of low or high demand. The electricity generated would then be sent back to the mainland. Onshore wind farms have smaller size and are spread over many sites. Current projects across the world aim at developing storage facilities for their production. The size of the farm impacts the type of technology selected. Flow batteries with 1 MW power content could suit for small wind farms (<5 MW) while NaS batteries with power content up to 10 MW are already being exploited as support for larger wind farms.

The chart above gives a possible illustration of the three different scenarios and highlights the technologies that could be considered in Belgium for energy storage purpose. Besides the estimated €4 billion invested in renewables, a rough evaluation of the construction costs of each scenario has been computed and reveals that the storage alternative is estimated to be €1,9 billion more expensive than the classical scenario with only gas power plants.

? Conclusion

Energy storage technologies could be part of a more general solution that aims at coping with the future challenges that the energy system in Belgium will face. Different technologies are being developed or improved in several countries but Belgium lags behind in terms of energy storage solutions. However, innovation could be the key in order to challenge this status quo. Especially the exploitation of old coalmines or the project of artificial island could provide new storage facilities that would partially solve the problem of future lack of capacities by being in compliance with European energy program. The last pending question relates to the investments that are needed in order to set up that kind of program, especially in Belgium where current business climate is unstable.